مَنْ يَضْمَنْ لِي مَا بَيْنَ لَحْيَيْهِ، وَمَا بَيْنَ فَخِذَيْهِ؛ أَضْمَنْ لَهُ الْجَنَّةَ
Translation: Whoever guarantees me protection of what lies between the jaws and what lies between the thighs, I guarantee Paradise for that person.
Source: البخاري
يَضْمَنْ لِي means “guarantees me,” while أَضْمَنْ لَهُ answers it with “I guarantee for that person.” مَا بَيْنَ لَحْيَيْهِ literally refers to what is between the jaws—the tongue. مَا بَيْنَ فَخِذَيْهِ refers indirectly to the private parts. Both are indirect expressions, or kināyah.
Guarding the tongue includes avoiding lies, slander, backbiting, and needlessly hurtful speech. Guarding chastity entails modesty and appropriate sexual boundaries. These two trusts shape a person’s overall character.